Trench, Keyhole and Mound Gardening reuses plant materials

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Start your gardening endeavors this fall by using plant materials (organic matter) that you would normally put on the curb for pick-up. Whether you use the trench, keyhole, mound (also known as Hugelkultur) gardening methods, you will be creating a growing environment that requires no fertilizer, little irrigation and ideal for root growth.

From a fertility standpoint, 10 percent organic matter is preferred for vegetables and flowers. Typically, in Illinois the percentage of organic matter is less than 2 percent, therefore requiring additions of fertilizers to keep plants green and blooming. However, fertility also can be achieved from the breakdown of organic matter.

Trench gardening is the simple way of composting organic matter without the pile. In your garden, dig a one-foot-deep hole, chop and mix kitchen scraps, straw, leaves, etc. then cover with 8 inches of soil. Depending on soil temperature, the supply of microorganisms (decomposers) and the content of the materials, decomposition will occur in one month to one year. Grow your plants in-between rows of these actively composting trenches. Rotate trenches every two to three years.

Keyhole gardening is a raised-bed system that uses a compost basket to add nutrients. Build a raised bed in a 6-foot-diameter circle at waist height with a wedge cut out for easy access out of found materials like cinder blocks. Layer the bottom with cardboard, branches, stems, newspapers then fill in spaces with kitchen and garden scraps, leaves and straw, top off with soil and mulch. Add a cylinder basket a foot wide made out of chicken wire to protrude out of the center. Add composting materials to the basket and periodically water. The soil should lead away from the basket causing the water to run off onto the existing plants, therefore providing nutrients.

Mound gardening resembles the decomposition found on the forest floor. Layer logs, branches, newspaper, kitchen scraps, leaves, egg shells, coffee grounds and top off with soil and start growing immediately. As the materials start to break down, they will create a soil filled with rich organic matter and air spaces. The heat given off in the decomposition process will create a longer growing season in the first few years but a bed mounded up high can give 20 years of nutrients.

Rules to follow when choosing materials:

  • Do not use cedar or locust; they take too long to rot. Do not use black walnut, which is toxic to plants, or black cherry, which is toxic to animals. Ideal logs are from alders, cottonwoods, poplar and birch.
  • Earthworms are more likely to be attracted to rich organic environments, giving added benefit with their castings.